The main problem of Mars is that there's nothing on it. If you have a ship that can get you to Mars, you might as well stay on it: the view is better, you don't have to live like a mole person, and you aren't at the bottom of a giant gravity well. Go checkout some asteriods or something.
Most likely if we actually built a city of people on Mars, life would be similar to living on an earth city but with low-G and you never go outdoors. We'd replicate typical earth city attractions and add a low-G spin where it was appropriate. Access to nature would be a problem (expensive fake Earth hab dome, dangerous outdoor games, no unfiltered sunlight on your skin, etc.)
Elon's ravings notwithstanding, what makes sense to me is extensive robotic exploration of Mars, perhaps operated by a skeleton crew of people who don't need quite the extensive training and qualifications of an astronaut. With enough exploring, experimenting and digging and we're likely to find something very exciting.
If you'd have to recycle your water and raw materials anyways, why not do it someplace where a dome crack won't kill everybody?
I think we should go to space (in O'Neil cylinders), but I'm going to spend some time thinking about desert wasteland arcologies.
Mars is appealing partly because it'll be a long time before it's crowded enough for any of that to matter.
Even if mankind is quite resilient, our current society is super fragile to much smaller catastrophe, and we may actually loose the ability for inter-planetary travel easily.
We really need to diversify our location. That's not the goal of this century, and probably not even the next one, but to have some skeleton seed of civilization elsewhere than here is a logical must, and Mars is easiest and closest one. So better start doing some baby steps towards that direction immediately when we can, rather than pour trillions into more than useless warfare.
I used to think we should fix issues here on Earth before moving elsewhere, but the problem is, we won't. Its dangerously naive idea. Rather we should accept that mankind is flawed and accept and work with flaws, compared to wait for some utopia to happen here and then expand.
https://www.cambridge.org/core/journals/international-journa...
The ozone layer would then of course shrink worldwide, yes, and this would collapse a large part of photosynthesis, causing a probable food chain collapse, but we're impressively adaptable and at the very least, millions of human beings would stay alive sustaining themselves with food grown or raised under adaptive conditions. The rest of nature would also adapt based on what survives, as it always has with previous cataclysms. This would probably help us too.
In other words, humanity would suffer terribly and billions would probably die, especially since this kind of event would be so sudden and unstoppable, but we wouldn't all die and the many survivors would repopulate as the ozone layer regrows too (which would happen over a few decades since it regenerates itself from solar radiation). But yes, bad. There is a theory that a gamma ray burst caused the Permian-Triassic event, the Great Dying, and 95% of life on Earth was extinguished during that time, though much of it was much less adapted to unexpected radiation than many lifeforms on Earth are now, so things could be less severe next time.
In reality, there is no 'unused' land on Earth, because we share the planet with other living beings. Earth has a biosphere that is already severely degraded by humanity's destruction of natural habitats
Once there, of course, after a single trip around the hab can (can hab?), you would start counting days ... sols ... until you could go home. Presuming it would be possible and permitted. If not, sucks to be you. Mars is a frozen wasteland with nothing of enduring interest.
The only export of any value conceivable would be excess Raptor engines taken off of landers, with their bells cut off.
If they do, and if you then saw one of your fellow travelers eating an interesting-looking sandwich, and you wanted to find out what it was, you would have the rare perk of walking up and dropping a pun that's been decades in the making:
"Can hab cheeseburger?"
You need, at least, two cans to swing at ends of a boom so your crew does not arrive unable to walk. You might want something attached at the axis, besides. That thing might do all the boosting, with the cans' Raptors used just to land with. ISRU fantasies notwithstanding, they need to carry enough fuel to blast off again, come time to go home.
The cans get benefit of aerobraking on the way down. The mainframe will need to shed its excess velocity some other way. There's nothing else near enough by to swing around. It will need to have brought along enough fuel to boost home, besides. Maybe it used ion thrusters all the way out, and can use them to creep back to Mars in time to pick up the cans and head home.
An alternative is that there is no mainframe, just the boom, and you re-fold and stow it before arrival. Somebody else would have boosted your cans out there, maybe a pair of Superheavys, so your cans won't have to arrive empty.
I wonder if a Superheavy with no can stacked on could make it to orbit in one stage. Probably you would unship their engines on orbit, and install a couple of vacuum Raptors in their place before sending them careering out of the solar system.
For a free-return trajectory (end up back at Earth if you’re not willing or able to conduct a Mars entry burn), the minimum-energy trajectory takes 250 days (8.3 months) and requires 3.34 km/s delta-V. Getting it down to 180 days takes 5.08 km/s, so about 50% more delta-V (and fuel). Getting there faster is possible but starts to run into diminishing returns, especially because it makes aerobraking at Mars more and more difficult, requiring even more fuel for slowing down on arrival.
These numbers are from Robert Zubrin’s “The Case for Mars” (1996) which assumed a six-month transit time would be the norm for human missions.
Fantasies of moving to Mars to escape climate change are stupid—even under the best terraforming projections and the worst climate change projections, Earth will be several orders of magnitude more habitable for centuries at least. But the scientific return from a once-warm-and-wet world is more than enough reason to go. Someone like NASA’s Jessica Watkins, who did her dissertation on Martian geology at Caltech, certainly would not be counting down the sols.
Put a human in the alien landscape of space (not to mention far away planets) and you may discover new (maddening) sensations. Like being heavily dosed on a narcotic cocktail. Disorientation. Detachment.
Oh wait. That’s Burning Man. Haha